Dictionary

Queries on dictionary tables are slow in Oracle Multitenant?

Posted on February 10, 2025 by Flaws and Pitfalls Single-/Multitenant 12

I love to learn something new every day. And on Friday afternoon last week I learned something new again. It started (as often) with a very simple question from a colleague working from the Oracle Malaga office in Spain. The customer has an issues with some queries being slower than before once they moved from on-prem to the cloud into a PDB. But are queries on dictionary tables are slow in Oracle Multitenant generally?

What was the case?

The customer ran some queries against dictionary views in the PDB in Oracle Database …

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Why does a PDB require an upgrade?

Posted on July 24, 2015 by Single-/Multitenant 0

Why do I need to upgrade (or downgrade) a Pluggable Database (PDB) once I unplug it from version A and replug into version B?

This question is one of the most often asked questions in our workshops when Roy and I present Upgrades and Oracle Multitenant.

If you take a look into the documentation you’ll find:

But unfortunately this is not 100% correct for every object.

When you do a simple query for basic dictionary structures such as OBJ$ you’ll easily find out that a PDB has its own Data Dictionary.  Some things are really linked …

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Mike Dietrich
Oracle Vice President of Product Management and Development for Database Upgrade, Cloud Migrations and Patching writing just another blog.

Opinions certainly are my own as is this page.

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